Known vehicle seats have a switching mechanism that switches a seat condition according to the shape and size of the passenger who is sitting on the seat. Examples of such switching mechanisms are a sliding mechanism for sliding the seat with respect to a floor, a reclining mechanism for tilting a seat back (i.e., a back rest) relative to a seat cushion (i.e., the portion on which the passenger sits), and a jump mechanism for quickly moving the seat upward from the floor into a folded position. Generally speaking, the switching mechanism is locked in order to hold the seat in a specific condition and is unlocked in order to allow the seat condition to be switched. Therefore, the switching mechanism is required to lock in a stable manner so as to prevent unintentional unlocking. A reclining mechanism, which is a typical switching mechanism, will now be described in detail.
Recent vehicle seats provide reclining mechanisms on both sides of the seat. Each of such vehicle seats has a structure in which a manipulation lever is provided on one side of the seat in order to switch the reclining mechanism from a locked condition to an unlocked condition. In such a structure, movement of the manipulation lever is directly transmitted to the reclining mechanism that is coupled to the manipulation lever (hereinafter referred to as an input side reclining mechanism). On the other hand, the movement of the manipulation lever is transmitted via a transmission member to the reclining mechanism that is not coupled to the manipulation lever (hereinafter referred to as an output side reclining mechanism). One known example of this type of vehicle seat utilizes a control cable that serves as a transmission member (e.g., Japanese Unexamined Utility Model Publication No. 3-39442).
In the vehicle seat disclosed in the above-described Publication, one end of the control cable is coupled to a manipulation lever and the other end of the control cable is coupled to an output side manipulation member. When the manipulation lever is rotated, the end of the control cable that is coupled to the manipulation lever is pulled (stroked) and the length of the stroke is transmitted to the output side manipulation member. Consequently, the output side manipulation member only pivots by the amount of transmitted stroke length and the output side reclining mechanism is actuated.
However, the vehicle seat described in the above Publication has the following problems. That is, the control cable that connects the reclining mechanisms, which are provided on both sides of the vehicle seat, includes an inner cable, which transmits the stroke length, and an outer casing, which is disposed around the inner cable. The respective ends of the outer casing are fixed to each respective side of the seat cushion of the vehicle seat. One end of the inner cable is coupled to the manipulation lever. The other end thereof is coupled to the output side manipulation member. The control cable connects the manipulation lever to the output side manipulation member such that the control cable extends along the outside of the vehicle seat. Therefore, the control cable does not extend in a straight line, but rather extends along a curved line.
When the manipulation lever is pivoted and the inner cable is pulled, the inner cable contacts the outer casing and a compressive force acts on the outer casing. As a result, the inner cable stretches and the outer casing shrinks. Consequently, the movement of the manipulation lever is not satisfactorily transmitted to the output side manipulation member (i.e., a stroke length loss results), so that actuation of the output side reclining mechanism fails. For such reason, control cables have not been used as a transmission member. Instead, another member, such as a rod, has been used as the transmission member.
As described above, in the known vehicle seat having the plurality of switching mechanisms that switch the seat condition, the manipulation force applied to the input side mechanism is not adequately transmitted to the output side mechanism when the input side mechanism and the output side mechanism are actuated via the cable. Therefore, the seat can not be reliably switched between a locked condition and unlocked condition.
Accordingly, it is an object of the present invention to provide vehicle seats capable of reliably actuating the output side mechanism using a control cable that minimizes stroke length loss.